A Feasible Application of Circular Economy: Spent Grain Energy Recovery in the Beer Industry

The generation of residual streams and wastes is a common constant in all productive processes. The brewing sector generates a large quantity of residual by-products which can be sustainably reused within the industry to contribute to cover the energy requirement of the process and at the same time to contribute to minimize the amount of waste that is sent to landfills. In this paper the feasibility and advantages of incorporating a stage for energy recovery from some of the solid wastes generated during the process as part of the circular economy approach is presented. La Cibeles, a local small size beer process is taken as a real example. In a brewing process the main wastes that are produced are: grain husks, yeast and CO2. Out of the three, the most important one is the grain husk or brewers' spent grain that can make around 85% of the total waste of a brewery. The results presented in this study show that, by gasification of brewers' spent grain, not only the final volume of the residue to be disposed is considerably minimised, but also it is possible to obtain a net economic saving of around 22% in the consume of fossil fuels used in the brewing process when the syngas produced is used for heat generation.